Hi gents...pardon me for jumping in, but I noticed you were chatting about an amp that I'm working on (Line 6 Spider - the first one, 112)....and I thought I'd bounce a question of of ya!  (Haven't found a schematic for it yet...)

The amp, as it stands, has an issue in that it won't get a clean tone....or I should say that it's very, very quiet in clean mode.  The distortion tones are there....I think there's something going on that may not be repairable (at least that's what the shop told me).

So I'd like to try something else with the amp...I'd like to just use the power output section of the amp, and provide it an input signal from my new POD floor pedal (HD500)...so I've opened it up and I see the LM4765 chip, and can tell that they are running it in Bridged Mode...(from doing a little DVM work).  What I'd like to do is to insert my POD signal so that I could use the amps Master Volume knob and LM4765 chip to provide the power amp output to the 112 speaker in the cab.   

I'm not able to tell where to insert the signal...I've traced the Master V pot and can see it come into the board, but I don't understand how that is working with the circuitry to be used as a master. 

Could I just inject the audio out of the POD to the inputs of the LM4765 (I think I'd need some kind of resistor between the insert point and the pin inputs 7 & 13, but not sure what value)....

Any thoughts on this would be great!  Thanks,
G~